Catalyst assist agents using leaving group effects

ABSTRACT

Leaving group effects provide a number of advantages in processing of cellulosic or cellulose-containing textiles. In particular, the rate of reaction of agents or compounds with cellulose can be increased in two ways. First, the reactivity of derivatives of N-methylol type agents and the reactivity of derivatives of hemiformals can be increased by proper choice of leaving group. Second, the leaving group forms a material which is acidic enough to assist in the catalysis of reactions with cellulose.

United States Patent [19 1 1 1 Sept. 30, 1975 Vail 1 1 CATALYST ASSISTAGENTS USING LEAVING GROUP EFFECTS [75] inventor: Sidney L. Vail, NewOrleans. La.

[73] Assignee: The United States of America as represented by theSecretary of Agriculture, Washington. DC.

221 Filed: Apr. 6. 1973 1211 Appl. No: 348,559

Related U.S. Application Data [621 Division of Ser. No. 267.312. June29. 1972. Pat. No;

[52] U.S. Cl. 8/181; 252/429 R [51] Int. C13... 006M 13/34 158] Field ofSearch 252/429 R; 8/181 115.5.

[56] References Cited UNITED STATES PATENTS 3.518.1144 6/1970 Reinhardt8/129 3.771.950 11/1973 Schwartz.... 8/186 3.772.292 11/1973 Martin8/186 5/1974 Gamarra 8/129 OTHER PUBLICATIONS Textile Research Journal,Principles of Reactivity of Nitrogenous Agents with Cotton," April 1970,Vol. 40. pp. 355-362.

Primary I;'.\'uminer-Benjamin R. Padgett Assistant Examiner-Donald P.Walsh Attorney Agent. or Firm-M. Howard Silverstein; Max D. Hensley [57]ABSTRACT type agents and the reactivity of derivatives of hemiformalscan be increased by proper choice of leaving group. Second. the leavinggroup forms a material which is acidic enough to assist in the catalysisof reactions with cellulose.

4 Claims, No Drawings CATALYST ASSIST AGENTS USING LEAVING GROUP EFFECTSA nonexclusive, irrevocable, royalty-fee license in the invention hereindescribed throughout the world for all purposes of the United StatesGovernment, with the power to grant sublicenses for such purposes, is

. hereby granted to the Government of the United States of America. 5

This is a division of application Ser. No. 267,312 filed June 29, 1972now US. Pat. No. 3,771,957. 7

This invention relates to the treatment of cellulosic textile materialsto produce textiles having improved physical and chemical properties,such as durablepress, flame resistance, weather resistance, anddimensional stability. Specifically, this invention relates to theprocess for treating cotton or other cellulosic fabrics withformulations which contain chemical compounds which are activated byleaving group effects thereby imparting to treated fabrics wrinkleresistance and durable-press properties. More specifically, the presentinvention relates primarily to the useof reactive catalyst assist agentswherein the leaving group from the catalyst assist agent forms amaterial which is acidic enough to assist in the catalysis of thereactions with cotton. In general, these catalyst assist agents areuseful in acid catalyzed processes in resin applications, textilefinish- In an acid-catalyzed reaction X may be considered to combinewith a proton to form HX whereas the intermediate ion may be consideredto react with cellulose to form:

R(CO)NHCH O Cellulose Heretofore, the textile industry has primarilybeen concerned with reaction systems wherein X was OH or occassionallyOCH and the leaving group, by addition of a proton, formed water (HOH)or methanol (HOCH In such cases the leaving group effect (where R isconstant or unchanged and X=OH or OCl-l has only a minor influence onthe relative reactivity of these reagents. Thus, the major influence onthe relative reaction rates is determined primarily by electronic andsteric efforts produced by R if the leaving group is limited to thoseusual cases where X=OH or OCH On the other hand, when the leaving groupforms secondary alcohols, such as cyclohexanol or isopropanol, and R isnot varied, there is a noticeable increase in reactivity over thecomparable reactant where X=OH or OCH Further, leaving groups whichforms organic acids, such as acetic acid, produce a noticeable increasein reactivity because of the leaving group effect.

There are a number of problems associated with this process. Theinteraction of intermediate ion stability and leaving group effects canresult in some cases where the relative reactivities of the reactantsare not predictable (See above references). Also, conversion ofN-methylol compounds into esterand ether-like compounds often reducesthe solubility of material in water and these new compounds are notsuitable for normal usage wherein aqueous solution are used in textilefinishing. in addition, agents which are made highly active by use of agood leaving group may hydrolyze in the pad bath and regenerate thestarting N-methylol agent or other corresponding intermediate products.Clearly, this occurrence defeats the purpose of preparing an activatedagent, because it is the rapid reaction with cellulose which is desired.

Derivatives of hemiformals or hemiacetals can function in a fashionsimilar to derivatives of N-methylol compounds in that the leaving groupeffect can both activate the molecule and also release an acid to assistin the reactions with cotton. The mechanism of these reactions arebelieved to be similar to those discussed previously in that reactivityis governed by intermediate ion stabililty and leaving group effects.Acyl derivatives of hemiacetals produce a mixed acetal of cellulosewhich may then react further to crosslink cellulose. For example, acylderivatives of hemiformals may react to form a cellulose alkyl formal,i.e., Cell OCH OR, which reacts further under acidic conditions to formCell OCl-l O Cell.

Recovery of a product from the leaving group must be considered in somecases. Volatile products of economic value, generally secondary alcoholsor acids, are released in processing-preferably during the curing operation. Release of large quanties of these materials can obviouslyproduce conditions dangerous to the health and safety of workers.

The primary object of the instant invention is to provide a type ofactivated reagent which can be used in textile finishing, especiallydurable-press, procedures as a catalyst assist agent, whereby theconventional curing catalyst is activated by release of unobjectionablequantities of acidic material from the activated agent.

These and other objects of the instant invention are accomplished bytreating the cellulosic textile with an aqueous solution containing a'crosslinking agent, such as dimethyloldihydroxyethyleneurea (hereafterreferred to as DMDHEU); a conventional curing catalyst, such asmagnesium chloride; and a catalyst assist agent which is neutral inaqueous solution but which forms an acid as strong or stronger thanacetic acid; i.e., acids in aqueous solutions at room temperature whichhave a dissociation constant greater than 10, on reaction with anucleophile such as cellulose, water, alcohol, and similar materials.

The chemical structures of the specific catalyst assist agents used inthe process of this invention are shown below:

CH O(CO)NHCH O(CO)CH The addition of these materials to a conventionaltextile treating solution has essentially no immediate effect upon thepH of the solution. However, the release of acetic acid duringprocessing markedly reduces the pH of the system.

The time of actual release of the acid is controlled by the treatmentconditions and by the reactivity of the catalyst assist agent, and, asnoted previously, the reactivity of these agents is controlled byintermediate ion stability and leaving group effects. Once release ofthe acid has begun, the reaction of the catalyst assist agent becomesauto-catalytic. In general, those acids which are relatively strong areproduced by the bctter leaving groups; whereas those acids which arerelatively weak are produced by leaving groups which do not activate theagent as much as do the aforementioned better leaving groups.

The volatility of the catalyst assist agent may also determine theeffectiveness of the agent Methoxymethyl acetate (boiling point about 118C) must release acetic acid relatively early in the curing process, ifheating at elevated temperatures is involved, or it could be removed bydistillation and might not be effective. However, acetoxymethyl methylcarbamate is less volatile and is not expected to distill from thefabric during a curing operation which requires heating.

On the other hand, it should be obvious to those skilled in the art thatvolatility of the catalyst assist agent would have essentially noinfluence upon the effectiveness of most processes wherein curing orfixation of reactants is carried out in the wet stage below the boilingpoint of the catalyst assist agent.

Similarly, the objectives of this invention can be met through use of asolvent system other than water. For example, isopropoxymethyl acetatehas a higher boiling point than methoxymethyl acetate and would be moresuitable for heat cures because of its lower volatility. However,isopropoxymethyl acetate is not soluble in water (less than 2% byweight) and therefore is preferably used in a nonaqueous system.

The explanations given above demonstrate the wide scope andapplicability of the present invention. Esterlike derivatives ofN-methylol compounds which release acids such as citric, tartaric,adipic, lactic glycolic, formic, and a-substituted acetic acids such ashydroxyacetic, methoxyacetic, cyanoacetic, chloroacetic and othersimilar acids are obvious examples of suitable derivatives to use ascatalyst assist agents. Also, the ester-like derivatives may be formedfrom monoor polyfunctional N-methylolamides, such as carbamates, ureas,melamines, formamides, acetamides, hydrazides, pyrrolidones and similaramide-like compounds. Further, the ester-like derivative may be formedby partial acylation of the crosslinking agent used in the fabrictreatment. Partial or total acylation of N, N- dimethylolamides toproduce a group or range of acylated products provides a useful methodfor obtaining catalyst assist agents of varying solubility andreactivity. Of particular interest are N,N-bis(acyloxymethyl )amideswhich are expected, in general, to be relatively stable materials, but,once these agents are activated, i.e., acid is released, the product ormonoacyloxymethylamide is expected to release acid at an acceleratedrate. Thus, placing two acyloxymethyl groups on a single nitrogen atomof an amide provides another way to control the rate of acid released tothe system.

The concentration of the crosslinking reactant in the pad bath can bevaried depending on the particular textile processing conditions used,the type of textile being treated, and the properties desired in thefinished textile. It is generally preferred to use about 2 to 20% byweight of the crosslinking reactant in the pad bath. A metal salt of astrong mineral acid is a suitable acidic catalyst to add to the treatingsolution of the process of the present invention. Magnesium chloride andzinc nitrate are examples of particularly suitable catalysts, and

concentrations of about from 0.2 to 3%, by weight, of the acidiccatalyst are generally preferred. The amount of the catalyst assistagent can be varied--depending upon the variables discussed above andconcentrations of about from 0.1 to 3% are generally preferred.Softeners and other additives may be used if desired.

Curing conditions can be varied widely as discussed above. Usually a dryimpregnated fabric is heated at about from lOOto lC for periods rangingfrom 15 to 0.5 minutes.

Following the curing operation it is preferablebut not necessarytowater-wash the treated textile to remove any unreacted materials. Thewashing operation can be carried out using the procedures and equipmentconventionally employed for the washing of textiles. After it is washedand dried, the treated testile has the same appearance as the originaluntreated textile, and its feel is also essentially unchanged; but thetreated fabric possesses resiliency, wrinkle resistance, and many otherdesirable properties.

The process of the instant invention can be used to treat substantiallyany hydrophilic fibrous cellulosic material such as cotton rayon, ramie,jute, and the like, which can be impregnated with a liquid and thencured.

The following examples are provided by way of illustration of how theinvention can be reduced to practice, and these are in no way meant toindicate limitation of the invention. The detailed procedures givenbelow in the examples are illustrative, and are not the only nor thespecific conditions for the production of an acceptable finishedtextile. Modification of these procedures can be made, as will beapparent to those skilled in the art. In the examples all parts andpercentages are by weight, unless noted otherwise.

The data in Table 1 demonstrate that the catalyst assist additivesdescribed in this invention, i.e., acetoxymethyl methyl carbamate andmethoxymethyl acetate, are effective in increasing the rate of reactionof DMDl-[EU with cotton and are also effective in increasing the rate atwhich the resilience or wrinkle recovery of the fabric is developed bythe-treatment.

EXAMPLE 1 Four aqueous solutions of 98 parts were prepared such that onaddition of 2 parts of one of the additives listed below, the finalconcentration of the pad bath was:

10% DMDHEU 4% MgCl -6H O 2% Additive The additives were as follows:

A. Water B. CH OCH O(CO)CH Because 2 parts of C was not soluble in 98parts of the prepared solution, this pad bath was discarded and was notused.

EXAMPLE 2 Fabric treatments: Samples of 80 X 80 cotton printcloth weredipped in the solutions of Example 1 and padded under identicalconditions to give approximately the same wet add-on for each fabricpadded, i.e., four fabric samples were dipped into one of the threesolutions in Example 1 to give a total of twelve fabric samples. Thewet, impregnated fabrics were all dried 7 minutes at 60C and then curedas shown in Table 1. All samples were washed in a warm alkaline watersolution containing a nonionic detergent, and tumble dried. Selectivetesting was then performed on all twelve fabric samples and these dataare also presented in Table l for comparative evaluation.

Table 1 Fabric Treatment Fabric Properties Fabric Samples Cond.

Wrinkle Identified by Cure Recovery Additives used Cond. Angle Nitrogenin Example I min/C (W+F. deg.)

A 145/100 l72 0.21 A 3.0/100 l96 0.37 A /140 276 L A 10/140 279 L34 Bl.5/l()() I82 0.16 B 3.0/l00 217 0.7l B 15/140 272 l.l8 B /140 278 1.27

D l.5/l()() 224 078 D 10/100 237 0.96

Table 1-- Continued Fabric Treatment Fabric Properties Fabric SamplesCond.

Wrinkle ldentified by Cure Recovery Additives used Cond. Angle Nitrogenin Example I min/"C (W+F, deg.) ('73) D 274 L44 D 3.0/140 279 1.53

I claim: 1. A composition for crosslinking cellulosicsaid catalyst ismagnesium chloride.

1. A COMPOSITION FOR CROSSLINKING CELLULOSIC-CONTAINING TEXTILES, SAIDCOMPOSITION COMPRISING A. DIMETHYLOLDIHYDROXYETHYLENEUREA, B. A CATALYSTSELECTED FROM THE GROUP CONSISTING OF MAGNESIUM CHLORIDE AND ZINCNITRATE, AND C. N-ACETOXYMETHYL METHY, CARBAMATE.
 2. The composition ofclaim 1 wherein the catalyst is zinc nitrate.
 3. A catalyst system foracid-catalyzed reactions, said system comprising a. a catalyst selectedfrom the group consisting of magnesium chloride and zinc nitrate, and b.methoxymethyl acetate.
 4. A catalyst system according to claim 3, inwhich said catalyst is magnesium chloride.